The present invention relates to an electronic timepiece with a depth gauge.
U.S. Pat. Nos. 4,352,168 and 4,533,256 describe dive timers for displaying a depth and a bottom time during a dive.
Multifunctional watches have been developed and various functions are provided to electronic watches in recent years. Demand has recently become strong arisen for dive watches in the market, thus inevitably leading to demand for an electronic watch with a depth gauge. A depth gauge circuit is arranged as an additional function in a conventional electronic watch with a depth gauge which comprises a timepiece circuit, a display unit and a battery. The display unit and the battery are used in both time and depth display modes, and these modes are selectively performed upon switching.
In the conventional electronic watch with a depth gauge, the timepiece circuit and the depth gauge circuit are selectively used while the battery and the display unit are always used to perform time or depth display. For example, even when the battery voltage drops to disable normal operation of the depth gauge circuit, the depth gauge circuit is operated and displays an incorrect water depth which differs from the actual water depth. In this case, a user or diver believes the wrong depth displayed on his watch and continues to dive, endangering his life. Furthermore, external operation members (pushbuttons or the like) are mounted on the conventional electronic watch with a depth gauge. The waterproof property of the watch is degraded upon operation of the external operation members, and water may enter inside the watch.